[U-Boot] [PATCH 026/126] pci: sandbox: Move the emulators into their own node
Bin Meng
bmeng.cn at gmail.com
Sat Oct 5 05:03:24 UTC 2019
On Wed, Sep 25, 2019 at 10:58 PM Simon Glass <sjg at chromium.org> wrote:
>
> Sandbox i2c works using emulation drivers which are currently children of
pci
> the i2c device:
pci
>
> pci-controller {
> pci at 1f,0 {
> compatible = "pci-generic";
> reg = <0xf800 0 0 0 0>;
> emul at 1f,0 {
> compatible = "sandbox,swap-case";
> };
> };
> };
>
> In this case the emulation device is attached to pci device on address
> f800 (device 1f, function 0) and provides the swap-case functionality.
>
> However this is not ideal, since every device on a PCI bus has a child
> device. This is only really the case for sandbox, but we want to avoid
> special-case code for sandbox.
>
> Worse, child devices cannot be probed before their parents. This forces
> us to use 'find' rather than 'get' to obtain the emulator device. In fact
> the emulator devices are never probed. There is code in
> sandbox_pci_emul_post_probe() which tries to track when emulators are
> active, but at present this does not work.
>
> A better approach seems to be to add a separate node elsewhere in the
> device tree, an 'emulation parent'. This could be given a bogus address
> (such as -1) to hide the emulators away from the 'pci' command, but it
> seems better to keep it at the root node to avoid such hacks.
>
> Then we can use a phandle to point from the evice to the correct
typo: device
> emulator, and only on sandbox. The code to find an emulator does not
> interfere with normal pci operation.
>
> Add a new UCLASS_PCI_EMUL_PARENT uclass which allows finding an emulator
> given a bus, and finding a bus given an emulator. Update the existing
> device trees and the code for finding an emulator.
>
> This brings PCI emulators more into line with I2C.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
> arch/sandbox/dts/sandbox.dtsi | 11 +++++++---
> arch/sandbox/dts/test.dts | 38 +++++++++++++++++++++++------------
> doc/driver-model/pci-info.rst | 23 +++++++++++----------
> drivers/pci/pci-emul-uclass.c | 37 ++++++++++++++++++++++++++++------
> include/dm/uclass-id.h | 1 +
> 5 files changed, 77 insertions(+), 33 deletions(-)
>
> diff --git a/arch/sandbox/dts/sandbox.dtsi b/arch/sandbox/dts/sandbox.dtsi
> index c6d5650c20b..f09bc70b0da 100644
> --- a/arch/sandbox/dts/sandbox.dtsi
> +++ b/arch/sandbox/dts/sandbox.dtsi
> @@ -103,9 +103,14 @@
> pci at 1f,0 {
> compatible = "pci-generic";
> reg = <0xf800 0 0 0 0>;
> - emul at 1f,0 {
> - compatible = "sandbox,swap-case";
> - };
> + sandbox,emul = <&swap_case_emul>;
> + };
> + };
> +
> + emul {
> + compatible = "sandbox,pci-emul-parent";
> + swap_case_emul: emul at 1f,0 {
> + compatible = "sandbox,swap-case";
> };
> };
>
> diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts
> index 5669ede7051..a2e75981f0b 100644
> --- a/arch/sandbox/dts/test.dts
> +++ b/arch/sandbox/dts/test.dts
> @@ -452,24 +452,31 @@
> pci at 0,0 {
> compatible = "pci-generic";
> reg = <0x0000 0 0 0 0>;
> - emul at 0,0 {
> - compatible = "sandbox,swap-case";
> - };
> + sandbox,emul = <&swap_case_emul0>;
&swap_case_emul0_0
> };
> pci at 1,0 {
> compatible = "pci-generic";
> reg = <0x0800 0 0 0 0>;
> - emul at 0,0 {
> - compatible = "sandbox,swap-case";
> - use-ea;
> - };
> + sandbox,emul = <&swap_case_emul1>;
&swap_case_emul0_1
> };
> pci at 1f,0 {
> compatible = "pci-generic";
> reg = <0xf800 0 0 0 0>;
> - emul at 1f,0 {
> - compatible = "sandbox,swap-case";
> - };
> + sandbox,emul = <&swap_case_emul1f>;
&swap_case_emul0_1f
> + };
> + };
> +
> + pci-emul0 {
> + compatible = "sandbox,pci-emul-parent";
> + swap_case_emul0: emul at 0,0 {
> + compatible = "sandbox,swap-case";
> + };
> + swap_case_emul1: emul at 1,0 {
> + compatible = "sandbox,swap-case";
> + use-ea;
> + };
> + swap_case_emul1f: emul at 1f,0 {
> + compatible = "sandbox,swap-case";
> };
> };
>
> @@ -499,9 +506,14 @@
> pci at 1f,0 {
> compatible = "pci-generic";
> reg = <0xf800 0 0 0 0>;
> - emul at 1f,0 {
> - compatible = "sandbox,swap-case";
> - };
> + sandbox,emul = <&swap_case_emul2_1f>;
> + };
> + };
> +
> + pci-emul2 {
> + compatible = "sandbox,pci-emul-parent";
> + swap_case_emul2_1f: emul2 at 1f,0 {
> + compatible = "sandbox,swap-case";
> };
> };
>
> diff --git a/doc/driver-model/pci-info.rst b/doc/driver-model/pci-info.rst
> index d93ab8b61d5..f39ff990a67 100644
> --- a/doc/driver-model/pci-info.rst
> +++ b/doc/driver-model/pci-info.rst
> @@ -113,14 +113,17 @@ Sandbox
> -------
>
> With sandbox we need a device emulator for each device on the bus since there
> -is no real PCI bus. This works by looking in the device tree node for a
> -driver. For example::
> -
> +is no real PCI bus. This works by looking in the device tree node for an
> +emulator driver. For example::
>
> pci at 1f,0 {
> compatible = "pci-generic";
> reg = <0xf800 0 0 0 0>;
> - emul at 1f,0 {
> + sandbox,emul = <&emul_1f>;
> + };
> + pci-emul {
> + compatible = "sandbox,pci-emul-parent";
> + emul_1f: emul at 1f,0 {
> compatible = "sandbox,swap-case";
> };
> };
> @@ -130,14 +133,16 @@ Note that the first cell in the 'reg' value is the bus/device/function. See
> PCI_BDF() for the encoding (it is also specified in the IEEE Std 1275-1994
> PCI bus binding document, v2.1)
>
> +The pci-emul node should go outside the pci bus node, since otherwise it will
> +be scanned as a PCI device, causing confusion.
> +
> When this bus is scanned we will end up with something like this::
>
> `- * pci-controller @ 05c660c8, 0
> `- pci at 1f,0 @ 05c661c8, 63488
> - `- emul at 1f,0 @ 05c662c8
> + `- emul at 1f,0 @ 05c662c8
>
> -When accesses go to the pci at 1f,0 device they are forwarded to its child, the
> -emulator.
> +When accesses go to the pci at 1f,0 device they are forwarded to its emulator.
>
> The sandbox PCI drivers also support dynamic driver binding, allowing device
> driver to declare the driver binding information via U_BOOT_PCI_DEVICE(),
> @@ -164,7 +169,3 @@ When this bus is scanned we will end up with something like this::
> pci [ + ] pci_sandbo |-- pci-controller1
> pci_emul [ ] sandbox_sw | |-- sandbox_swap_case_emul
> pci_emul [ ] sandbox_sw | `-- sandbox_swap_case_emul
> -
> -Note the difference from the statically declared device nodes is that the
> -device is directly attached to the host controller, instead of via a container
> -device like pci at 1f,0.
> diff --git a/drivers/pci/pci-emul-uclass.c b/drivers/pci/pci-emul-uclass.c
> index 38227583547..f918e9a52fd 100644
> --- a/drivers/pci/pci-emul-uclass.c
> +++ b/drivers/pci/pci-emul-uclass.c
> @@ -10,6 +10,7 @@
> #include <linux/libfdt.h>
> #include <pci.h>
> #include <dm/lists.h>
> +#include <dm/uclass-internal.h>
>
> struct sandbox_pci_emul_priv {
> int dev_count;
> @@ -30,13 +31,15 @@ int sandbox_pci_get_emul(struct udevice *bus, pci_dev_t find_devfn,
> }
> *containerp = dev;
>
> - if (device_get_uclass_id(dev) == UCLASS_PCI_GENERIC) {
> - ret = device_find_first_child(dev, emulp);
> - if (ret)
> - return ret;
> - } else {
> + /*
> + * TODO(sjg at chromium.org): This code needs a comment as I'm not sure
> + * why UCLASS_PCI_GENERIC devices end up being their own emulators. I
> + * left this code as is.
> + */
This code comes from:
commit 4345998ae9dfad7ba0beb54ad4322134557504a9
Author: Bin Meng <bmeng.cn at gmail.com>
Date: Fri Aug 3 01:14:45 2018 -0700
pci: sandbox: Support dynamically binding device driver
I think the comments can be removed :)
> + ret = uclass_find_device_by_phandle(UCLASS_PCI_EMUL, dev,
> + "sandbox,emul", emulp);
> + if (ret && device_get_uclass_id(dev) != UCLASS_PCI_GENERIC)
> *emulp = dev;
> - }
>
> return *emulp ? 0 : -ENODEV;
> }
> @@ -68,3 +71,25 @@ UCLASS_DRIVER(pci_emul) = {
> .pre_remove = sandbox_pci_emul_pre_remove,
> .priv_auto_alloc_size = sizeof(struct sandbox_pci_emul_priv),
> };
> +
> +/*
> + * This uclass is a child of the pci bus. Its platdata is not defined here so
> + * is defined by its parent, UCLASS_PCI, which uses struct pci_child_platdata.
> + * See per_child_platdata_auto_alloc_size in UCLASS_DRIVER(pci).
> + */
> +UCLASS_DRIVER(pci_emul_parent) = {
> + .id = UCLASS_PCI_EMUL_PARENT,
> + .name = "pci_emul_parent",
> + .post_bind = dm_scan_fdt_dev,
> +};
> +
> +static const struct udevice_id pci_emul_parent_ids[] = {
> + { .compatible = "sandbox,pci-emul-parent" },
> + { }
> +};
> +
> +U_BOOT_DRIVER(pci_emul_parent_drv) = {
> + .name = "pci_emul_parent_drv",
> + .id = UCLASS_PCI_EMUL_PARENT,
> + .of_match = pci_emul_parent_ids,
> +};
> diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
> index d4d96106b37..f431f3bf294 100644
> --- a/include/dm/uclass-id.h
> +++ b/include/dm/uclass-id.h
> @@ -23,6 +23,7 @@ enum uclass_id {
> UCLASS_I2C_EMUL, /* sandbox I2C device emulator */
> UCLASS_I2C_EMUL_PARENT, /* parent for I2C device emulators */
> UCLASS_PCI_EMUL, /* sandbox PCI device emulator */
> + UCLASS_PCI_EMUL_PARENT, /* parent for PCI device emulators */
> UCLASS_USB_EMUL, /* sandbox USB bus device emulator */
> UCLASS_AXI_EMUL, /* sandbox AXI bus device emulator */
>
> --
Other than the issues above,
Reviewed-by: Bin Meng <bmeng.cn at gmail.com>
Tested-by: Bin Meng <bmeng.cn at gmail.com>
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